       ;; It finds the first block that matches earliest-time
       ;; It's going to re-send that block (it *does* exist...right?)
       (let [block (first un-ackd-blocks)
-            state (assoc-in state [::specs/outgoing ::specs/next-block-queue] ::specs/un-ackd-blocks)]
+            state' (assoc-in state [::specs/outgoing ::specs/next-block-queue] ::specs/un-ackd-blocks)]
         ;; But first, it might adjust some of the globals.
         (if (> recent (+ last-panic (* 4 rtt-timeout)))
           ;; Need to update some of the related flow-control fields
-          (-> state
+          (-> state'
               (update-in [::specs/flow-control ::specs/n-sec-per-block] * 2)
               (assoc-in [::specs/outgoing ::specs/last-panic] recent)
               (assoc-in [::specs/flow-control ::specs/last-edge] recent))
           ;; We haven't had another timeout since the last-panic.
           ;; Don't adjust those dials.
-          state)))
+          state')))
     (do
       ;; Honestly, it makes more sense to consolidate the
       ;; gap-buffer with any ACKs in this message before


(s/fdef check-for-previous-block-to-resend
        :args ::specs/state
        :ret (s/nilable ::specs/state))
(defn check-for-previous-block-to-resend
  "Returns a modified state to resend, or nil if it's safe to move on to something fresh
;;;  339-356: Try re-sending an old block: (DJB)
;;;           Picks out the oldest block that's waiting for an ACK
;;;           If it's older than (+ lastpanic (* 4 rtt_timeout))

  ;; TODO: Instead of returning nil on nothing to do, just
  ;; do something like setting a nil cursor.
  ;; That should simplify the caller.
  (let [found? (check-for-previous-block-to-resend state)]
    (if (get-in found? [::specs/outbound ::specs/next-block-queue])
      found?)
;;;       357-410: Try sending a new block: (-- DJB)
     ;; There's goto-fun overlap with resending
     ;; a previous block -- JRG
    (check-for-new-block-to-send state)))

(s/fdef block->parent!
        :args (s/cat :send-buf ::specs/buf)
